The present invention relates to nutritional disturbances in bovine associated with ingestion of plant protein antigens and more particularly to vaccines for bovine effective for overcoming such disturbances of immunological origin.
A relationship between the poor performance of pre-ruminant fed on milk replacer having soy protein as a major ingredient and a component of the soy protein that is antigenic to the animal has been demonstrated through the production of high titers of antibody to the soy protein in the blood serum. Nutritional disturbances are not manifested on the first introduction of soy protein into the bovine diet. The animals exhibit such changes upon second and subsequent feedings of soy protein which generally coincides with demonstrable serum antibody, strongly leading researchers in the field to suggest an immunological basis for these interferences with physiological function.
It is believed that sufficient intact macromolecules can be absorbed to induce both local and systemic immune responses. This state of immunity may manifest itself in a protective function, or a destructive function being mediated as a hypersensitivity reaction. Some authors have suggested that hot aqueous ethanol extraction of soybean meal is effective in reducing the apparent antigenic nature of the product (Guilloteau et al., "Effective Soya Protein on Digestive Enzymes, Gut Hormone and Anti-Soya Antibody Plasma Levels in the Pre-Ruminant Calf", Reprod. Nutr. Develop., 26 (2B), 717-728, 1986), though most investigators report that the harmful antigen clearly survives such extraction technique.
The intestinal mucosa of pre-ruminant bovine is affected by a variety of foreign substances, many of which, under the appropriate stimulation, can act as antigens. Ingested foodstuffs are among such foreign substances which can evoke an adverse immunologic reaction. Local synthesis and secretion of immunoglobulin within the intestinal mucous membrane primarily is responsible for the prevention of the absorption of antigen. The major immune response to dietary soya protein antigen, for example, in the young calf has been demonstrated to be an IgGl precipitant capable of fixing complement (C). The antigen-antibody reaction that occurs in the lamina propia of the intestinal tract results in hemorrhage, edema, and monocellular infiltration. The villi of the intestine become shorter and broader, thus decreasing the absorptive area and the efficiency of digestion. In some instances, the calf will develop a hypersensitive reaction to the soy protein. These calves usually exhibit a selective anorexia to soy milk and do not gain weight. A good discussion of this subject can be found by Barratt et al. "Immunologically Mediated Nutritional Disturbances Associated with Soya-Protein Antigens", Proc. Nutr. Soc. (1979), 38, 143, and Barratt et al., "Immunoglobulin Classes Implicated in Intestinal Disturbances of Calves Associated with Soya Protein Antigens", The Journal of Immunology, (1979) 123 (2): 676-680.